The closing line of Isaac's blessing, as the Targum Pseudo-Jonathan renders it, reaches beyond Jacob and names two future figures by name. "Let them who curse thee, my son, be accursed as Bileam bar Beor; and them who bless thee be blessed as Mosheh the prophet, the scribe of Israel" (Genesis 27:29).
Balaam. Moses. Two men who have not yet been born.
Why these two names?
Because in the rabbinic reading, Balaam and Moses are the two great opposing forces in Israel's early history. Balaam, son of Beor, is the gentile prophet hired by Balak to curse Israel in the wilderness (Numbers 22-24); his curses turn, against his will, into blessings. Moses, the greatest of Israel's prophets, blesses Israel again and again, and his blessings stand forever.
Pseudo-Jonathan is giving Isaac a prophetic horizon. The patriarch sees, through the mist of centuries, the two archetypes of hostility and love toward his descendants, and he sets them as the measuring rods. To curse Jacob's children is to be as doomed as Balaam. To bless them is to share in the fate of Moses — the scribe of Israel, the one who wrote the Torah down.
Peoples and kingdoms
The earlier lines of the verse are equally layered. Let peoples be subject to thee, all the sons of Esau, and kingdoms bend before thee, all the sons of Keturah. The Targum specifies which nations — Edom, descended from Esau, and the Arabian tribes descended from Keturah, Abraham's later wife. The blessing is not vague. It is geopolitical.
The takeaway: Isaac's blessing, spoken over a single son on a single night, is a map of all the peoples and all the prophets who will ever rise for or against Jacob's children. The scope is staggering.